Solid acetylene



Patented res. 5,1952

SOLID ACETYLENE Rudolph Leonard Hasche, Johnson City, Tenn.

No Drawing. Application August 24, 1949, Serial No. 112,187

6 Claims.

This invention relates to solid acetylene. More particularly, the invention relates to a new compressed and briquetted form of solid acetylene and to the production thereof.

Acetylene is conventonally shipped either in the form of calcium carbide in nonreturnable steel drums or as a gas dissolved in a suitable solvent, such as acetone, and maintained under pressure in cylinders. Both of these expedients are markedly disadvantageous, however, for the reason that the acetylene constitutes a small percentage of the gross weight of commercial package and shipping and handling charges are therefor inordinately high.

The distribution of acetylene in the form of calcium carbide is additionally disadvantageous in that it necessitates the installation of an expensive acetylene generator by the consumer. The acetylene obtained from such a generator is normally contaminated with water, ammonia, and in some instances organic materials, such as phosphene. The presence of such contaminants greatly detracts from the utility and commercial value of the acetylene.

Similarly, acetylene derived from solutions thereof maintained under pressure is conventionally contaminated with an appreciable amount of the solvent utilized.

The commercial utilization of solid acetylene has heretofore been deemed infeasible. Solid acetylene has been considered a laboratory curiosity subject to violent explosive decomposition upon the application of pressure or excessive heat. Furthermore, solid acetylene at its sublimation temperature readily liquefies when subjected to an absolute pressure equal to or greater than about 1.18 atmospheres. Hence, it has been deemed impossible from a practical standpoint to produce compressed blocks of solid acetylene.

Now in accordance with this invention, it has been found that compressed solid acetylene may be produced and preserved in an economical and practical manner by subjecting a cooled, compressed gaseous mixture containing acetylene to adiabatic expansion thereby to produce solid acetylene at a temperature substantially below the melting point thereof, compressing the solid acetylene so formed before the temperature thereof rises to a point at which such compres sion would result in liquefaction and encasing the solid acetylene block so formed in solid carbon dioxide.

It is essential to the process of this invention that the solid acetylene not liquefy when compressed. This result is achieved by producing 25 the solid acetylene from a mixture of gases, rather than from substantially pure acetylene. Thus the solid acetylene is obtained in the. first instance at a temperature substantially below its melting point.

In accordance with the process of this invention, a compressed gaseous mixture containing acetylene is cooled, preferably to a temperature only slightly above the solidification temperature thereof at the prevailing pressure. The compressed, cooled gas is then expanded adiabatically with the production of external work, whereby the temperature thereof is reduced to a point substantially below the solidification temperature of acetylene at the various pressures involved. A substanti .1 portion of the acetylene is thus caused to separate in a finely divided form.

This finely divided solid acetylene is then compressed into a block or other desired configuration before the temperature thereof rises to a point at which such compression would result in liquefaction.

The total pressure to which the acetylene containing gas is subjected may vary over a wide range dependent upon the relative concentration of acetylene in the particular gaseous mixture utilized. For example, pressures within the range of 10-25 atmospheres are preferably utilized for gaseous mixtures containing not more than about fifteen percent by volume of acetylene, whereas for gases richer in acetylene a pressure of about five atmospheres is desirable.-

In any event, however, the total pressure to which the acetylene containing gaseous mixture is subjected must be such that the partial pressure of the acetylene is below 1.18 atmospheres absolute, the pressure which obtains at the triple point of acetylene. That is, the partial pressure of the acetylene must be such that upon subsequent cooling and expansion, the acetylene will pass directly from the gaseous to the solid phase.

The compression of the acetylene containing gaseous mixture may be effected by conventional methods, and may'take place either in a single or in a plurality of stages.

In the interest of efllciency, it is desirable to cool the compressed acetylene containing gaseous mixture to a temperature only slightly above minus 83.6 C., the sublimation temperature of acetylene. Preferably the compressed gaseous mixture is cooled to a temperature within the range of from about minus C. to about minus C.

lhe cooling of the compressed gas may be efted by any suitable means known to the art. counter current gas to gas heat exchanger quite suitable for this purpose.

the adiabatic expansion of the cooled, com- :ssed acetylene containing gaseous mixture .y likewise be achieved by conventional meth- The finely divided solid acetylene so produced then compressed into a block or other desired nfiguration before the temperature thereof :es to a point at which such compression would sult in liquefaction.

It has been discovered that solid acetylene may fely be compressed at temperatures of about lnus 90 C. or below. It is preferred, however. at the acetylene be compressed at a temperare not higher than about minus 95 C. Presre as great as one thousand pounds per square ch gauge may be employed. The solid acetyne may be compressed by any appropriate eans known to the art, it being only essential .at the acetylene be not thereby liquefied.

It is preferred that the gaseous mixture from riich the solid acetylene is derived contain from nout five to about fifteen percent by volume of :etylene, although gaseous mixtures containing mewhat greater or lesser amounts of acetylene ay be utilized. It is essential to production "{solid acetylene atthe proper temperature, ivvever, that the gaseous mixture employed con- .in not more than about twenty percent by )lume of acetylene.

The crude gaseous mixtures resulting from the .gh temperature cracking of hydrocarbons are irticularly for the use in the process of this lvention. These crude gaseous mixtures nor- .ally contain acetylene in amounts falling in ie aforementioned ranges in conjunction with w molecular weight olefins and paraiflns, carin monoxide, hydrogen and the like.

The briquet or block of compressed solid acetyne is preserved and prepared for shipping in :cordance with this invention by encasing it or irrounding it with solid carbon dioxide. If esired, solid carbon dioxide which has been prouced by known methpds may be compressed or riquetted about the preformed acetylene block nd the block thus encased in a shell of solid arbon dioxide. Alternatively, the compressed )lid acetylene may be surrounded or stored in lternating layers with compressed solid acetyene. The composite product in any event should e surrounded by appropriate insulation.

The thickness of the solid carbon dioxide shell r of the solid carbon dioxide slabs which should e utilized depends upon the period of time beween the production of the composite block nd the utilization of the acetylene and the onditions of storage during that period. It is ssential that the solid acetylene be maintained t approximately the temperature of the solid :arbon dioxide until it is consumed. Those skilled in the art will be well aware of the proper quantity and thickness of solid carbon dioxide fr employ in any particular instance.

In some instances, it may be desirable to omit the shell of carbon dioxide and preserve the compressed acetylene by means of appropriate insulation of the type conventionally used to effect the preservation of solid carbon dioxide may be utilized for this purpose.

When it is desired to utilize the solid acetylene, the shell or surrounding layer of carbon dioxide is removed and the pure solid acetylene permitted to sublime. It will be appreciated that once the compressed solid acetylene is formed at a temperature appreciably below the sublimation point, the acetylene will absorb heat and rise in temperature until it reaches the sublimation point of about minus 835 C. The solid acetylene at that temperature will then sublime without decomposition or liquefaction, provided the vapor pressure does not exceed about 1.18 atmospheres until all the acetylene is completely vaporized.

It will be appreciated that the production of briquetted solid acetylene in accordance with the methods of this invention eliminates to a large extent the excessive and inordinate shipping and handling costs which attend the aforementioned conventional methods of dispensing the product. Furthermore, the methods of the present invention result in the delivery to the consumer of acetylene of high purity. Hence, the value and utility-of the acetylene resultant from the process of this invention is much greater than tha of acetylene dispensed by methods now utilized.

Also, of great importance is the fact that there is no significant loss of acetylene by sublimation or otherwise when solid acetylene is preserved by the method of this invention.

The following examples are offered as specific embodiments of this invention:

Example I produced. This solid acetylene was immediately compressed into a briquette. A pressure of about eight hundred and fifty pounds per square inch gauge was utilized. The compression of the solid acetylene was completed before the temperature thereof had risen above about minus 90 C.

There was then compressed about the exterior of the solid acetylene block, a layer of solid carbon dioxide about one inch thick. The entire composite briquette was then encased in insuiation of the type utilized to preserve solid carbon dioxide. The solid carbon dioxide utilized was produced by the method of U. S. Patent 2,011,551 to Hasche.

Several days later the insulation and the remainder of the carbon dioxide encasing were removed from the solid acetylene block. No difliculty was experienced in removal 01' the carbon dioxide casing;

No loss of solid acetylene by sublimation or otherwise was detectable. The acetylene block slowly sublimed at room temperature to form substantially pure acetylene gas.

Example I! A solid acetylene block-weighing approximately two kilograms was prepared in that described in Example I. In this case, however, the acetylene block was encased in individual slabs of solid compressed carbon dioxide without the application of abnormal pressure, and the resulting aggregate block encased in suitable insulation.

Several days later the insulation and carbon dioxide slabs were removed from the solid acetylene block with the same result as that described in Example I.

The foregoing specification is given by way 01 exemplification of the invention and not in limitation thereof, the scope of the invention being that of the subjoined claims.

What is claim is:

l. Compressed solid acetylene encased in solid carbon dioxide.

2. A composite briquet comprising a block of solid acetylene encased in solid carbon dioxide.

3. A method for packaging acetylene which comprises subjecting an acetylene containing, compressed, cooled gaseous mixture, said mixture not containing more than about by volume of acetylene, to adiabatic expansion thereby to produce solid acetylene at a temperature substantially below the melting point thereof, compressing the solid acetylene so formed before the temperature raises to a point at which such compression would effect liquefaction of the solid acetylene and encasing the compressed acetylene insolid carbon dioxide.

4. A method for packaging acetylene which comprises compressing an acetylene containing gaseous mixture, said mixture not containing more than about 20% .by volume of acetylene, sufllciently that the partial pressure of the acetylene is such that upon cooling it will pass directly from the gaseous to the solid phase, cooling the compressed gaseous mixture to a temperature not more than about 10 higher than that at which the acetylene would solidify under prevailim conditions, expanding the cooled oompresset gaseous mixture adlabatically thereby to producl solid acetylene at a temperature substantially below the meltingpoint thereof, compressing the solid acetylene so formed before the temperature thereof raises to a point at which such compression would result in liquefaction of the solid acetylene, and encasing the solid acetylene so formed in solid carbon dioxide. 5. The process of claim 4- wherein the compressed solid acetylene is encased in solid carbon dioxide by compressing finely divided solid car bon dioxide around the compressed solid acetyene. Y

6. The process which comprises compressing an acetylene containing gaseous mixture, said mixture not containing more than about 20% by volume of acetylene, sufficiently that the partial pressure of the acetylene is such that upon cooling it will pass directly from the gaseous to the solid phase, cooling the compressed gaseous mixture to a temperature not more than about 10 higher than that at which the acetylene would solidify under prevailing conditions, expanding the cooled compressed gaseous mixture adiabatically thereby to produce solid acetylene at a temperature substantially below the melting point thereof, compressing the solid acetylene so formed before the temperature thereof raises to a point at which such compression would result in liquefaction of the solid acetylene.

RUDOLPH LEONARD HASCHE.

REFERENCES crrizn I The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,600,308 Blanchard Sept. 21, 1926 1,730,923 Field Oct. 8, 1929 2,014,245 Donahoe Sept. 10, 1935 FOREIGN PATENTS Number Country Date 145,769 Switzerland June 1, 1931 351,63% Great Britain July 2, 1931 

1. COMPRESSED SOLID ACETYLENE ENCASED IN SOLID CARBON DIOXIDE. 